Method of manufacturing a semiconductor device having a power metallization structure

ABSTRACT

A semiconductor device includes a semiconductor substrate, a power metallization structure formed above the semiconductor substrate and a barrier layer formed between the power metallization structure and the semiconductor substrate. The barrier layer is configured to prevent diffusion of metal atoms from the power metallization structure in a direction toward the semiconductor substrate. The power metallization structure is in direct contact with the barrier layer or an electrically conductive layer formed on the barrier layer in a first region. The semiconductor device further includes a passivation layer interposed between the barrier layer and the power metallization structure in a second region. Corresponding methods of manufacturing the semiconductor device are also described.

BACKGROUND

Copper is widely used as a power metallization in semiconductor devices.However, when a copper film is subjected to temperature cycling, thecopper film undergoes elastic and plastic deformation which inducesstress on the surrounding elements such as the barrier, ILD (interlayerdielectric), passivation, etc. The stress induced by the copper film canlead to one or more failure modes such as cracks in the passivationand/or in the device substrate, delamination between the copper filmmetal and the barrier, etc. The induced stress is strongly dependent onmorphology of the power metal after structuring. Hence, improvedmeasures are needed for mitigating the stress induced by copper filmsused in semiconductor devices.

Moreover, thick copper has low routing density due to low pitch. Anincrease in routing density can be realized by adding additional routinglayers, which includes metal deposition and patterning, ILD depositionfor insulation, and via etch to connect the metal layers. This adds tothe overall cost of the semiconductor device. For power technologieswith thick copper metallization and bonding on active areas, additionalsofter (e.g. aluminum) layers increase the layout complexity. Copperdamascene processes circumvent such problems, but at extremely highadditional costs. Hence, improved measures are needed for increasingrouting density when using copper metallization in semiconductordevices.

SUMMARY

According to an embodiment of a semiconductor device, the semiconductordevice comprises: a semiconductor substrate; a power metallizationstructure formed above the semiconductor substrate; a barrier layerformed between the power metallization structure and the semiconductorsubstrate, the barrier layer configured to prevent diffusion of metalatoms from the power metallization structure in a direction toward thesemiconductor substrate, the power metallization structure being indirect contact with the barrier layer or an electrically conductivelayer formed on the barrier layer in a first region; and a passivationlayer interposed between the barrier layer and the power metallizationstructure in a second region.

In an embodiment, the barrier layer may be structured in the secondregion as a signal routing structure.

Separately or in combination, the power metallization structure may bedisposed over the signal routing structure in the second region and thesignal routing structure may be insulated from the power metallizationstructure by the passivation layer in the second region.

Separately or in combination, the power metallization structure may bestructured independently of the signal routing structure in the secondregion.

Separately or in combination, the first region and the second region maybe directly adjoining, the power metallization structure and the barrierlayer may be unpatterned in the first region and the second region, andthe passivation layer may cover a periphery of the barrier layer in thesecond region.

Separately or in combination, the barrier layer may laterally extendbeyond side faces of the power metallization structure in the secondregion.

Separately or in combination, the barrier layer may laterally extendbeyond side faces of the power metallization structure in the secondregion by between 500 nm and 5 microns.

Separately or in combination, the passivation layer may be interposedbetween the barrier layer and the power metallization structure in asection of the second region spaced apart from the first region.

Separately or in combination, the barrier layer may be structured as asignal routing structure in the section of the second region spacedapart from the first region.

Separately or in combination, the power metallization structure may bedisposed over the signal routing structure in the section of the secondregion spaced apart from the first region and the signal routingstructure may be insulated from the power metallization structure by thepassivation layer.

Separately or in combination, the power metallization structure may bestructured independently of the signal routing structure in the sectionof the second region spaced apart from the first region.

Separately or in combination, the semiconductor device may furthercomprise an intermediate layer interposed between the barrier layer andthe passivation layer in the second region, and the intermediate layermay be structured identically as the barrier layer in the second region.

Separately or in combination, the barrier layer may comprise TiW, theintermediate layer may comprise AlCu and the power metallizationstructure may comprise Cu.

Separately or in combination, the semiconductor device may furthercomprise an intermediate layer interposed between the passivation layerand the power metallization structure in the second region.

Separately or in combination, the barrier layer may comprise TiW, theintermediate layer may comprise TiW and the power metallizationstructure may comprise Cu.

Separately or in combination, the power metallization structure may beomitted above the barrier layer in the second region.

According to an embodiment of a method of manufacturing a semiconductordevice, the method comprises: forming a barrier layer above asemiconductor substrate, the barrier layer configured to preventdiffusion of metal atoms from above the barrier layer in a directiontoward the semiconductor substrate; structuring the barrier layer; andafter structuring the barrier layer, forming a power metallizationstructure above the structured barrier layer without forming anadditional barrier layer for the power metallization structure, thepower metallization structure being in direct contact with the barrierlayer or an electrically conductive layer formed on the barrier layer ina first region.

In an embodiment, forming the power metallization structure maycomprise: after structuring the barrier layer, forming an adhesionpromoting layer on the barrier layer and a Cu layer on the adhesionpromoting layer, the adhesion promoting layer configured to increaseadhesion of the power metallization structure to the barrier layer inthe first region; forming a mask on the Cu layer, the mask havingopenings aligned with features previously structured into the barrierlayer; and isotropically etching the Cu layer and the adhesion promotinglayer through the openings in the mask, to structure the powermetallization structure and so that the barrier layer laterally extendsbeyond side faces of the power metallization structure in regionsaligned with the openings in the mask. In the case of Cu metallization,the adhesion promoting layer may not be bound to the (thick) Cu layerafter sputtering and etching, but may instead be formed as part of anelectro-chemical deposition (ECD) process used to form the Cu layer.

Separately or in combination, the method may further comprise: beforestructuring the barrier layer, forming a protective layer on the barrierlayer which is configured to prevent oxidation of the barrier layerduring the structuring.

Separately or in combination, forming the power metallization structuremay comprise: after structuring the protective layer and the barrierlayer, forming a Cu seed layer on the protective layer; forming a maskon the Cu seed layer in a second region; forming a Cu layer on the Cuseed layer in the first region but not in the second region where themask is present; and after forming the Cu layer, removing the mask andthe Cu seed layer from the protective layer in the second region.

Separately or in combination, forming the power metallization structuremay comprise: after structuring the protective layer and the barrierlayer, forming a passivation layer on the protective layer; removing thepassivation layer in the first region but not in a second region;forming a Cu seed layer on the protective layer in the first region andon the passivation layer in the second region; and forming a Cu layer onthe Cu seed layer at least in the first region.

Separately or in combination, the method may further comprise: beforeforming the Cu layer, forming a mask on the Cu seed layer in the secondregion so that the Cu layer is formed on the Cu seed layer in the firstregion but not in the second region where the mask is present; and afterforming the Cu layer, removing the mask.

Separately or in combination, the method may further comprise: afterremoving the mask, removing the Cu seed layer from the passivation layerin the second region.

Separately or in combination, the Cu layer may be formed in the firstregion and in the second region and the passivation layer may beinterposed between the barrier layer and the Cu layer in the secondregion.

Separately or in combination, the barrier layer may be structured in thesecond region as a signal routing structure and the method may furthercomprise: structuring the Cu layer in the second region independently ofthe signal routing structure.

Separately or in combination, forming the power metallization structuremay comprise: after structuring the protective layer and the barrierlayer, forming a passivation layer on the protective layer; removing thepassivation layer in the first region but not in a second region; andforming a Cu layer on the protective layer in the first region and onthe passivation layer in the second region by physical vapor deposition.

Separately or in combination, the method may further comprise: removingthe Cu layer from the passivation layer in the second region.

Separately or in combination, the barrier layer may be structured in thesecond region as a signal routing structure and the method may furthercomprise: structuring the Cu layer in the second region independently ofthe signal routing structure.

Separately or in combination, the protective layer may be deposited insitu with the barrier layer and the protective layer and the barrierlayer may be structured concurrently.

Separately or in combination, the protective layer may comprise AlCu andthe barrier layer may comprise TiW.

Separately or in combination, forming the protective layer may comprise:depositing a layer of oxide on the barrier layer using atomic layerdeposition.

Those skilled in the art will recognize additional features andadvantages upon reading the following detailed description, and uponviewing the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

The elements of the drawings are not necessarily to scale relative toeach other. Like reference numerals designate corresponding similarparts. The features of the various illustrated embodiments can becombined unless they exclude each other. Embodiments are depicted in thedrawings and are detailed in the description which follows.

FIG. 1 illustrates a partial sectional view of an embodiment of asemiconductor device.

FIGS. 2A through 2E illustrate an embodiment of a method ofmanufacturing the semiconductor device shown in FIG. 1.

FIG. 3 illustrates a partial sectional view of another embodiment of asemiconductor device.

FIG. 4 illustrates a partial sectional view of another embodiment of asemiconductor device.

FIGS. 5A through 5F illustrate an embodiment of a method ofmanufacturing a semiconductor device.

FIGS. 6A through 6H illustrate another embodiment of a method ofmanufacturing a semiconductor device.

FIGS. 7A through 7G illustrate another embodiment of a method ofmanufacturing a semiconductor device.

FIGS. 8A through 8E illustrate another embodiment of a method ofmanufacturing a semiconductor device.

DETAILED DESCRIPTION

The embodiments described herein provide a semiconductor device thatincludes a semiconductor substrate, a power metallization structureformed above the semiconductor substrate, and a barrier layer formedbetween the power metallization structure and the semiconductorsubstrate. The barrier layer prevents diffusion of metal atoms from thepower metallization structure in a direction toward the semiconductorsubstrate. The power metallization structure is in direct contact withthe barrier layer or an electrically conductive layer formed on thebarrier layer in a first region, and a passivation layer is interposedbetween the barrier layer and the power metallization structure in asecond region. In one embodiment, the barrier layer is structured as asignal routing structure in the second region. According to thisembodiment, signal routing structure is implemented by the barrier layerand not the overlying power metallization structure which may have lowerrouting density due to its relatively thick construction compared to thebarrier layer. In another embodiment, the first region and the secondregion are directly adjoining, the power metallization structure and thebarrier layer are unpatterned in the first region and the second region,and the passivation layer covers a periphery of the barrier layer in thesecond region. According to this embodiment, a washer-like structure isformed in the second region and includes the passivation layerseparating the barrier layer from the power metallization structure. Thewasher-like structure surrounds the first region where the powermetallization structure and the barrier layer are not separated from oneanother by the passivation layer. In another embodiment, thesemiconductor device includes both the signal routing structure and thewasher-like structure. Corresponding manufacturing methods are alsodescribed.

FIG. 1 illustrates a partial sectional view of a semiconductor device.The semiconductor device includes a semiconductor substrate 100, a powermetallization structure 102 formed above the semiconductor substrate100, and a barrier layer 104 formed between the power metallizationstructure 102 and the semiconductor substrate 100. The barrier layer 104may be in contact with the semiconductor substrate 100 as shown in FIG.1, or may be separated from the semiconductor substrate 100 by one ormore insulating layers. In either case, the semiconductor substrate 100may be any type of semiconductor substrate typically used to implementlogic and/or power semiconductor devices. For example, the semiconductorsubstrate 100 may be a Si substrate, a Si-on-insulator (SOI) substrate,a GaN substrate, a SiC substrate, a GaAs substrate, another type ofIII-V or II-VI substrate, etc.

Various power metallization structure/barrier layer combinations arecontemplated. For example, the power metallization structure 102 maycomprise Cu and the barrier layer 104 may comprise at least one of Ti,TiW, W and Ta. In another embodiment, the power metallization structure102 comprises Al or an Al alloy and the barrier layer 104 comprises atleast one of Ti, TiN and W. In yet another embodiment, the powermetallization structure 102 comprises Au and the barrier layer 104 iscompatible with Au. A common barrier layer for at least Cu and Al metalsystems is TiW. Still other power metallization structure/barrier layercombinations are possible.

The barrier layer 104 is configured to prevent diffusion of metal atomsfrom the power metallization structure 102 in a direction toward thesemiconductor substrate 100. For example, in the case of Cumetallization, the barrier layer 104 may comprise TiW or any othersuitable metal layer or stack of metal sublayers configured to preventdiffusion of Cu atoms from the power metallization structure 102 in adirection toward the semiconductor substrate 100.

In a first region 106 of the semiconductor device, the powermetallization structure 102 is in direct contact with the barrier layer104 or an intermediate electrically conductive layer 108 formed on thebarrier layer 104. That is, there is direct electrical contact betweenthe power metallization structure 102 and the barrier layer 104 orintermediate layer 108 formed on the barrier layer 104 in the firstregion 106 of the semiconductor device.

In one embodiment, the intermediate layer 108 is an electricallyconductive adhesion promoting layer configured to increase adhesion ofthe power metallization structure 102 to the underlying barrier layer104 in the first region 106. For Cu metallization, the barrier layer 104may comprise a relatively thick layer of TiW whereas the intermediatelayer 108 may comprise a relatively thin layer of TiW or Ti. Anintermediate layer 108 of TiW or Ti may be an ineffective barrieragainst the migration of Cu atoms if relatively thin, but increases theadhesion of the power metallization structure 102 to the barrier layer104 if formed as part of the power metallization structure process. Inthe case of Cu metallization, the adhesion promoting layer 108 may notbe bound to the (thick) underlying Cu layer after sputtering andetching, but may instead be formed as part of an electro-chemicaldeposition (ECD) process used to form the Cu layer.

A thin oxidation layer may inevitably form on the barrier layer 104during structuring. To achieve proper adhesion, the intermediate layer108 of TiW or Ti and thicker Cu metallization may be formed via the sameprocess. Alternatively, the oxidation may be prevented which isdescribed in the next embodiment.

In another embodiment, the intermediate layer 108 is an anti-oxidationlayer formed on the barrier layer 104 prior to structuring of thebarrier layer 104. As will be described in more detail later herein, thebarrier layer 104 is structured/patterned prior to formation of thepower metallization structure 102. Depending on the composition of thebarrier layer 104, the barrier layer 104 may oxidize when exposed duringthe structuring/patterning process. For example, TiW oxidizes whenexposed which may decrease the adherence of the barrier layer 104 to thepower metallization structure 102. The anti-oxidation layer 108 protectsthe barrier layer 104 from oxidation during structuring of the barrierlayer 104. For Cu metallization, the barrier layer 104 may comprise TiWwhereas the intermediate layer 108 may comprise AlCu. The intermediatelayer 108 of AlCu is effective at preventing oxidation of TiW and othertypes of barrier layer materials. Still other types of materials may beused for the intermediate layer 108. Depending on the composition of theintermediate layer 108 and processing parameters involved, theintermediate layer 108 may or may not be present in the first region 106of the final semiconductor device.

The semiconductor device also includes an electrically insulatingpassivation layer 110 interposed between the barrier layer 104 and thepower metallization structure 102 in a second region 112 of thesemiconductor device different than the first region 106. Theintermediate layer 108 is interposed between the barrier layer 104 andthe passivation layer 110 in the second region 112. In the case of theintermediate layer 108 being an anti-oxidation layer for the barrierlayer 104 as previously described herein, the intermediate layer 108 isstructured identically as the barrier layer 104 in the second region 112since the intermediate layer 108 is formed on the barrier layer 104before structuring of the barrier layer 104.

In a first section 112 a of the second region 112, the barrier layer 104may be structured as a signal routing structure 114. Since the barrierlayer 104 is significantly thinner than the power metallizationstructure 102, e.g. 2×, 5×, 10×, 20×, 50× or more thinner, the barrierlayer 104 has a higher routing density than the power metallizationstructure 102. The power metallization structure 102 may be disposedover the signal routing structure 114 in the first section 112 a of thesecond region 112 of the semiconductor device as shown in FIG. 1. Inthis case, the signal routing structure 114 is insulated from theoverlying power metallization structure 102 by the passivation layer 110in the first section 112 a of the second region 112. The powermetallization structure 102 may be structured independently of thesignal routing structure 114 in the first section 112 a of the secondregion 112. That is, since the signal routing structure 114 is formedbefore the power metallization structure 102, the power metallizationstructure 102 and the signal routing structure 114 may have different orindependent routing configurations.

In a second section 112 b of the second region 112 of the semiconductordevice, the first and second regions 106, 112 are directly adjoining.The power metallization structure 102 and the barrier layer 104 may beunpatterned in the first region 106 and in the second section 112 b ofthe second region 112, and the passivation layer 110 may cover theperiphery of the barrier layer 104 in the second section 112 b of thesecond region 112 to form a washer-like structure 116 in the secondregion 112 which includes the passivation layer 110 separating thebarrier layer 104 from the power metallization structure 102. Thewasher-like structure 116 surrounds the first region 106 where the powermetallization structure 102 and the barrier layer 104 are not separatedfrom one another by the passivation layer 110.

The barrier layer 104 may laterally extend beyond the side faces 118 ofthe power metallization structure 102 in the second section 112 b of thesecond region 112 to form the washer-like structure 116. For example,the barrier layer 104 may laterally extend beyond the side faces 118 ofthe power metallization structure 102 in the second section 112 b of thesecond region 112 by an amount x which is between 500 nm and 5 micronsto form the washer-like structure 116. The washer-like structure 116acts as a crack preventing compressive interlayer.

The semiconductor device may include both the barrier layer signalrouting structure 114 in the first section 112 a of the second region112 of the device and the washer-like structure 116 in the secondsection 112 b of the second region 112 of the device, e.g., as shown inFIG. 1. In this embodiment, the barrier layer 104 is structured as asignal routing structure 114 and the passivation layer 110 is interposedbetween the signal routing structure 114 and the power metallizationstructure 102 in the first section 112 a of the second region 112 of thesemiconductor device. The power metallization structure 102 may bedisposed over the barrier layer signal routing structure 114. In thiscase, the barrier layer signal routing structure 114 is insulated fromthe power metallization structure 102 by the passivation layer 110 inthe first section 112 a of the second region 112 of the device. Thepower metallization structure 102 may be structured independently of thebarrier layer signal routing structure 114 in the first section 112 a ofthe second region 112 of the device, as previously described herein.

FIGS. 2A through 2E illustrate an embodiment of a method ofmanufacturing the semiconductor device shown in FIG. 1.

FIG. 2A shows the semiconductor device after the intermediate layer 108is formed on the barrier layer 104, after the intermediate/barrier layerstack 104/108 is structured to form a signal routing structure 114 inthe first section 112 a of the second region 112 of the device, andafter the passivation layer 110 is formed on the structuredintermediate/barrier layer stack 104/108. According to this embodiment,the intermediate layer 108 is an anti-oxidation layer formed on thebarrier layer 104 prior to structuring of the barrier layer 104. Forexample, the barrier layer 104 may comprise TiW and the intermediatelayer 108 may comprise AlCu. In a more specific example, theintermediate layer 104 may be a 30-70 nm thick AlCu layer in-situdeposited on a TiW barrier layer 104. Subsequent alloying of such anAlCu intermediate layer 108 with a thick Cu power metallizationstructure 102 improves fatigue robustness.

In one embodiment, the barrier layer 104 is in-situ covered by theintermediate layer 108 so as to protect the barrier layer 104 fromoxidation during the subsequent structuring/patterning process. Theintermediate layer 108 may instead be formed ex-situ. Examples of theintermediate layer 108 include, but are not limited to, thin metal filmse.g. 30-70 nm AlCu or Ti, ultra-thin metal films e.g. 2 nm Au,ultra-thin interlayer dielectric layers e.g. ALD (atomic layerdeposited) Al₂O₃, etc.

The intermediate layer 108 may include one or more material sublayers,and is structured/patterned concurrently with the barrier layer 104according to the embodiment shown in FIG. 2A. The intermediate layer 108may remain on the barrier layer 104 through the end of manufacturing, ormay be removed or diffused in a later stage. For example, theintermediate layer 108 may be removed by a dedicated removal step beforebeginning to form the power metallization structure 102, by diffusion ofthe intermediate layer 108 into the barrier layer 104 and/or powermetallization structure 102 during subsequent annealing, etc. In thecase of an Al-based intermediate layer 108 and a TiW barrier layer 104,the intermediate layer 108 not only protects the barrier layer 104 fromoxidation during the subsequent structuring/patterning process, but alsoremains on the barrier layer routing structure 114 where it improves theconductivity of the barrier layer 104 which typically has a higherresistance.

The intermediate/barrier layer stack 104/108 may be structured/patternedconcurrently, e.g., by a lithography-assisted plasma etching processsuch as Cl- and/or F-based plasma etching processes. The resultingstructured intermediate/barrier layer stack 104/108 may be passivated bythe passivation layer 110. Any typical passivation material may be usedfor the passivation layer 110, e.g., such as silicon nitride and/orsilicon oxide. In the case of silicon nitride and/or silicon oxide, thepassivation layer 110 may be formed by chemical vapor deposition (CVD).The barrier layer routing and washer-like structures 114, 116 aredefined by the structuring/patterning process for theintermediate/barrier layer stack 104/108.

FIG. 2B shows the semiconductor device after a mask 200 such asphotoresist is formed on the passivation layer 110 and after theunprotected part of the passivation layer 110 is removed to expose thebarrier layer routing and washer-like structures 114, 116. For example,the passivation layer 110 may be lithographically processed and plasmastructured to define via or pad openings 202 to the underlying barrierlayer routing and washer-like structures 114, 116. The mask 200 is thenremoved.

FIG. 2C shows the semiconductor device after physical vapor deposition(PVD) of a Cu seed layer 204 over the remaining passivation layer 110and the exposed part of the intermediate layer 108. A Cu seed layer 204may be used in the case of a Cu power metallization structure 102. TheCu seed layer 204 may be omitted for other types of power metallizationmaterials such as Al, Au, etc. If the Cu seed layer 204 is used, a thinAl layer (not shown) may be formed on the passivation layer 110 toimprove adhesion between the passivation layer 110 and the subsequentlyformed power metallization structure 102.

FIG. 2D shows the semiconductor device after electro-chemical deposition(ECD) of a thick Cu power metal 206 on the Cu seed layer 204. A mask 208such as a photoresist may be used to prevent ECD of the thick Cu powermetal 206 in certain areas of the device, e.g., to allow for independentstructuring of the thick Cu power metal 206 over the routing structure114 formed by the barrier layer 104 which remains covered by thepassivation layer 110 in this region 112 a of the device. As shown inFIGS. 2C and 2D, the power metallization structure 102 is formed abovethe structured barrier layer 104 without forming an additional barrierlayer for the power metallization structure 102.

FIG. 2E shows the semiconductor device after the mask 208 is removed.The thick Cu power metal 206 may then be used as a hard mask forremoving the exposed Cu seed layer 204, e.g., by blanket wet etching.The passivation layer 110 ensures the underlying barrier layer routingstructure 114 is electrically insulated from the overlying powermetallization structure 102, if present over the routing structure 114.The semiconductor device is then annealed to complete the powermetallization structure 102. The resulting device is shown in FIG. 1.

As explained above, some or all of the intermediate layer 108 maydiffuse as a result of the annealing process. However, in other casesthere may be little to no diffusion of the intermediate layer 108. Inthese cases, the intermediate layer 108 remains essentially intact asshown in FIG. 1.

FIG. 3 illustrates an embodiment in which the intermediate layer 108remains essentially intact in the barrier layer routing and washer-likestructures 114, 116, but not in the region 106 where the passivationlayer 110 is removed. According to this embodiment, the intermediatelayer 108 diffuses into the power metallization structure 102 in thisregion 106 and the barrier layer 104 is in direct contact with the powermetallization structure 102.

FIG. 4 illustrates an embodiment in which the intermediate layer 108 isnot present as a defined layer in the final device. In one embodiment,the intermediate layer 108 is formed by ALD and is intrinsically removedby the subsequent ECD process used to form the power metallizationstructure 102 and therefore does not diffuse into either the barrierlayer 104 or the power metallization structure 102. In anotherembodiment, the intermediate layer 108 diffuses into the barrier layer104 and/or the power metallization structure 102. For example, in thecase of AlCu as the intermediate layer 108, constituent parts of Al maydiffuse into the barrier layer 104 and/or the power metallizationstructure 102 during the annealing process.

FIGS. 5A through 5F illustrate another embodiment of a method ofmanufacturing a semiconductor device having the barrier layer routingstructure 114.

FIG. 5A shows the semiconductor device after a barrier layer 104configured to prevent diffusion of metal atoms from above the barrierlayer 104 in a direction toward a semiconductor substrate 100 is formedover the substrate 100, and after an intermediate layer 108 such as ananti-oxidation layer is formed on the barrier layer 104. The barrierlayer 104 may be in contact with the semiconductor substrate 100 asshown in FIG. 5A, or may be separated from the semiconductor substrate100 by one or more insulating layers. In either case, the semiconductorsubstrate 100 may be any type of semiconductor substrate typically usedto implement logic and/or power semiconductor devices. The barrier layer104 may be in-situ or ex-situ covered by the intermediate layer 108 soas to protect the barrier layer 104 from oxidation during subsequentstructuring/patterning of the barrier layer 104, e.g., as previouslydescribed herein in connection with FIG. 2A.

FIG. 5B shows the semiconductor device after the intermediate layer 108and the barrier layer 104 are structured/patterned concurrently using amask 300, e.g., by a lithography-assisted plasma etching process such asCl- and/or F-based plasma etching processes, to define the barrier layerrouting structure 114. The mask 300 is then removed.

FIG. 5C shows the semiconductor device after PVD of a Cu seed layer 302over the structure. Cu is typically used as a seed layer 302 in the caseof Cu power metallization. The Cu seed layer 302 may be omitted forother types of power metallization materials such as Al, Au, etc.

FIG. 5D shows the semiconductor device after ECD of a thick Cu powermetal 304 on the Cu seed layer 302. According to this embodiment, a mask306 such as a photoresist is used to prevent ECD of the thick Cu powermetal 304 over the barrier layer routing structure 114. Accordingly, thepower metallization structure 102 is omitted above the barrier layerrouting structure 114. Different than the embodiment illustrated inFIGS. 2A through 2E, the passivation layer 110 between the intermediatelayer 108 and the power metallization structure 102 may be omitted sincethe power metallization structure 102 does not extend over the barrierlayer routing structure 114.

FIG. 5E shows the semiconductor device after the mask 306 is removed andafter using the thick Cu power metal 304 as a hard mask to remove theexposed Cu seed layer 302, e.g., by blanket wet etching.

FIG. 5F shows the semiconductor device after annealing which isperformed to complete the power metallization structure 102. Differentthan the semiconductor devices shown in FIGS. 1, 3 and 4, thesemiconductor device shown in FIG. 5F has no passivation layer betweenthe intermediate layer 108 and the power metallization structure 102 andthe power metallization structure 102 does not extend over the barrierlayer routing structure 114. As explained previously herein, some or allof the intermediate layer 108 may diffuse into the barrier layer 104and/or the power metallization structure 102 as a result of theannealing process, may be intrinsically removed by the ECD process usedto form the power metallization structure 102 and therefore does notdiffuse into either the barrier layer 104 or the power metallizationstructure 102, or may remain essentially intact.

FIGS. 6A through 6H illustrate another embodiment of a method ofmanufacturing a semiconductor device having the barrier layer routingstructure 114.

FIG. 6A shows the semiconductor device after a barrier layer 104configured to prevent diffusion of metal atoms from above the barrierlayer 104 in a direction toward a semiconductor substrate 100 is formedover the substrate 100, and after an intermediate layer 108 such as ananti-oxidation layer is formed on the barrier layer 104. The barrierlayer 104 may be in contact with the semiconductor substrate 100 asshown in FIG. 6A, or may be separated from the semiconductor substrate100 by one or more insulating layers. In either case, the semiconductorsubstrate 100 may be any type of semiconductor substrate typically usedto implement logic and/or power semiconductor devices. The barrier layer104 may be in-situ or ex-situ covered by the intermediate layer 108 soas to protect the barrier layer 104 from oxidation during subsequentstructuring/patterning of the barrier layer 104, e.g., as previouslydescribed herein in connection with FIG. 2A.

FIG. 6B shows the semiconductor device after the intermediate layer 108and the barrier layer 104 are structured/patterned concurrently using amask 400, e.g., as previously described herein in connection with FIG.2A, to define the barrier layer routing structure 114.

FIG. 6C shows the semiconductor device after a passivation layer 110 isformed on the structured intermediate/barrier layer stack 104/108, e.g.,as previously described herein in connection with FIG. 2A. The mask 400is then removed.

FIG. 6D shows the semiconductor device after another mask 402 such asphotoresist is formed on the passivation layer 110 and after theunprotected part of the passivation layer 110 is removed to expose theunderlying intermediate layer 108, e.g., as previously described hereinin connection with FIG. 2B.

FIG. 6E shows the semiconductor device after PVD of a Cu seed layer 404over the passivation layer 110 and the exposed part of the intermediatelayer 108, e.g., as previously described herein in connection with FIG.2C.

FIG. 6F shows the semiconductor device after ECD of a thick Cu powermetal 406 on the Cu seed layer 404. According to this embodiment, a mask408 such as a photoresist is used to prevent ECD of the thick Cu powermetal 406 over the barrier layer routing structure 114, e.g., aspreviously described herein in connection with FIG. 5D. Accordingly, thepower metallization structure 102 does not extend over the barrier layerrouting structure 114.

FIG. 6G shows the semiconductor device after the mask 408 is removed andafter using the thick Cu power metal 406 as a hard mask to remove theexposed Cu seed layer 404, e.g., as previously described herein inconnection with FIG. 5E.

FIG. 6H shows the semiconductor device after annealing which isperformed to complete the power metallization structure 102. Similar tothe semiconductor devices shown in FIGS. 1, 3 and 4, the semiconductordevice shown in FIG. 6H has a passivation layer 110 between theintermediate layer 108 and the power metallization structure 102 in oneregion of the device. Similar to the semiconductor device shown in FIG.5F, the power metallization structure 102 does not extend over thebarrier layer routing structure 114 for the semiconductor device shownin FIG. 6H in another region of the device. As explained previouslyherein, some or all of the intermediate layer 108 may diffuse into thebarrier layer 104 and/or the power metallization structure 102 as aresult of the annealing process, may be intrinsically removed by the ECDprocess used to form the power metallization structure 102 and thereforedoes not diffuse into either the barrier layer 104 or the powermetallization structure 102, or may remain essentially intact.

FIGS. 7A through 7G illustrate another embodiment of a method ofmanufacturing a semiconductor device having a barrier layer routingstructure.

FIG. 7A shows the semiconductor device after a barrier layer 104configured to prevent diffusion of metal atoms from above the barrierlayer 104 in a direction toward a semiconductor substrate 100 is formedover the substrate 100, and after an intermediate layer 108 such as ananti-oxidation layer is formed on the barrier layer 104. The barrierlayer 104 may be in contact with the semiconductor substrate 100 asshown in FIG. 7A, or may be separated from the semiconductor substrate100 by one or more insulating layers. In either case, the semiconductorsubstrate 100 may be any type of semiconductor substrate typically usedto implement logic and/or power semiconductor devices. The barrier layer104 may be in-situ or ex-situ covered by the intermediate layer 108 soas to protect the barrier layer 104 from oxidation during subsequentstructuring/patterning of the barrier layer 104, e.g., as previouslydescribed herein in connection with FIG. 2A.

FIG. 7B shows the semiconductor device after the intermediate layer 108and the barrier layer 104 are structured/patterned concurrently using amask 500, e.g., as previously described herein in connection with FIG.2A, to define the barrier layer routing structure 114.

FIG. 7C shows the semiconductor device after a passivation layer 110 isformed on the structured intermediate/barrier layer stack 104/108, e.g.,as previously described herein in connection with FIG. 2A.

FIG. 7D shows the semiconductor device after a mask 502 such asphotoresist is formed on the passivation layer 110 and after theunprotected part of the passivation layer 110 is removed to expose thebarrier layer routing structure 114, e.g., as previously describedherein in connection with FIG. 2B.

FIG. 7E shows the semiconductor device after PVD of a thick Cu powermetallization 504 over the passivation layer 110 and the exposed part ofthe intermediate layer 108. Different than the embodiment illustrated inFIGS. 2D, 5D and 6F, the thick Cu power metallization 504 is blanketdeposited and then subsequently patterned.

FIG. 7F shows the semiconductor device after a mask 506 such as aphotoresist is formed on the blanket-deposited thick Cu powermetallization 504 and after the exposed part of the thick Cu powermetallization 504 is etched, e.g., via a H₃PO₄—H₂O₂ etchant solution.

FIG. 7G shows the semiconductor device after annealing which isperformed to complete the power metallization structure 102.

FIGS. 8A through 8E illustrate an embodiment of a method ofmanufacturing a semiconductor device, wherein the intermediate layer 108is an adhesion promoting layer configured to increase adhesion of thepower metallization structure 102 to the barrier layer 104 in a regionof the device.

FIG. 8A shows the semiconductor device after a barrier layer 104configured to prevent diffusion of metal atoms from above the barrierlayer 104 in a direction toward a semiconductor substrate 100 is formedover the substrate 100. The barrier layer 104 may be in contact with thesemiconductor substrate 100 as shown in FIG. 8A, or may be separatedfrom the semiconductor substrate 100 by one or more insulating layers.In either case, the semiconductor substrate 100 may be any type ofsemiconductor substrate typically used to implement logic and/or powersemiconductor devices. The barrier layer 104 may be annealed withnitrogen to increase its ruggedness.

FIG. 8B shows the semiconductor device after the barrier layer 104 isstructured, e.g., by plasma etching process using a lithography mask(not shown) such as a photoresist. The reticle design of the lithographymask and the dimensions of the openings 600 formed in the barrier layer104 define the range of positive edge length (x) for the barrier layer104. The mask is then removed and the structure cleaned to remove maskresidue.

FIG. 8C shows the semiconductor device after a power metallizationprocess. An adhesion promoting intermediate layer 108 such as TiW or Tiis deposited in-situ with a thick Cu power metal layer 602 over thebarrier layer 104, e.g., via a sputter process. In this embodiment, theintermediate layer 108 acts as an adhesion promoter between theunderlying barrier layer 104 and the overlying thick Cu power metallayer 602. In another embodiment, the adhesion promoting intermediatelayer 108 is a TiW/Cu seed layer deposited over the barrier layer 104and the thick Cu power metal layer 602 is electrochemically depositedwith resist on the TiW/Cu seed layer. In either case, the adhesionpromoting intermediate layer 108 is substantially thinner than the Cupower metal layer 602, e.g., about 50 nm in the case of a TiW adhesionpromoting intermediate layer.

FIG. 8D shows the semiconductor device after a mask 604 such as aphotoresist is formed on the Cu power metal layer 602. The mask 604 hasopenings 606 aligned with the features previously structured into thebarrier layer 104.

FIG. 8E shows the semiconductor device after isotropically etching theCu power metal layer 602 and the adhesion promoting intermediate layer108 through the openings 606 in the mask 604 to structure/pattern thepower metallization structure 102. The isotropic etching provides awell-defined positive edge/step 608 in the barrier layer 104 withrespect to the power metallization structure 102. That is, the edges 608etched into the barrier layer 104 laterally extend further than theedges 610 etched into the power metallization structure 102.

The positive edge/step 608 in the barrier layer 104 increases thedistance for metal electromigration between a power terminal of thesemiconductor device and a control terminal of the device, and also moreuniformly distributes stress in the ILD induced during thermal cyclingof the power metallization structure 102. Accordingly, the positiveedge/step 608 in the barrier layer 104 reduces stress at the etched edge608 of the barrier layer 104 which may otherwise lead to cracks ordelamination. FIG. 8E includes an exploded region, which shows thebarrier layer 104 laterally extending beyond the etched side faces 610of the power metallization structure 102 in regions aligned with theopenings 606 in the mask 604 by an amount x which may be in a range,e.g., between 500 nm and 5 microns.

Terms such as “first”, “second”, and the like, are used to describevarious elements, regions, sections, etc. and are also not intended tobe limiting. Like terms refer to like elements throughout thedescription.

As used herein, the terms “having”, “containing”, “including”,“comprising” and the like are open ended terms that indicate thepresence of stated elements or features, but do not preclude additionalelements or features. The articles “a”, “an” and “the” are intended toinclude the plural as well as the singular, unless the context clearlyindicates otherwise.

It is to be understood that the features of the various embodimentsdescribed herein may be combined with each other, unless specificallynoted otherwise.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat a variety of alternate and/or equivalent implementations may besubstituted for the specific embodiments shown and described withoutdeparting from the scope of the present invention. This application isintended to cover any adaptations or variations of the specificembodiments discussed herein. Therefore, it is intended that thisinvention be limited only by the claims and the equivalents thereof.

What is claimed is:
 1. A method of manufacturing a semiconductor device,the method comprising: forming a barrier layer above a semiconductorsubstrate, the barrier layer configured to prevent diffusion of metalatoms from above the barrier layer in a direction toward thesemiconductor substrate; structuring the barrier layer; and afterstructuring the barrier layer, forming a power metallization structureabove the structured barrier layer without forming an additional barrierlayer for the power metallization structure, the power metallizationstructure being in direct contact with the barrier layer or anelectrically conductive layer formed on the barrier layer in a firstregion, wherein forming the power metallization structure comprises:after structuring the barrier layer, forming an adhesion promoting layeron the barrier layer and a Cu layer on the adhesion promoting layer, theadhesion promoting layer configured to increase adhesion of the powermetallization structure to the barrier layer in the first region;forming a mask on the Cu layer, the mask having openings aligned withfeatures previously structured into the barrier layer; and isotropicallyetching the Cu layer and the adhesion promoting layer through theopenings in the mask, to structure the power metallization structure andso that the barrier layer laterally extends beyond side faces of thepower metallization structure in regions aligned with the openings inthe mask.
 2. The method of claim 1, further comprising: beforestructuring the barrier layer, forming a protective layer on the barrierlayer which is configured to prevent oxidation of the barrier layerduring the structuring.
 3. The method of claim 2, wherein the protectivelayer comprises AlCu and the barrier layer comprises TiW.
 4. A method ofmanufacturing a semiconductor device, the method comprising: forming apower metallization structure above a semiconductor substrate; forming abarrier layer between the power metallization structure and thesemiconductor substrate, the barrier layer configured to preventdiffusion of metal atoms from the power metallization structure in adirection toward the semiconductor substrate, the power metallizationstructure being in direct contact with the barrier layer or anelectrically conductive layer formed on the barrier layer in a firstregion, a passivation layer being interposed between the barrier layerand the power metallization structure in a second region; andstructuring the barrier layer as a signal routing structure in thesecond region, wherein the power metallization structure is disposedover the signal routing structure in the second region, wherein thesignal routing structure is insulated from the power metallizationstructure by the passivation layer in the second region.
 5. The methodof claim 4, further comprising structuring the power metallizationstructure independently of the signal routing structure in the secondregion.
 6. The method of claim 4, wherein the first region and thesecond region are directly adjoining, wherein the power metallizationstructure and the barrier layer are unpatterned in the first region, andwherein the passivation layer covers a periphery of the barrier layer inthe second region.
 7. The method of claim 6, wherein the barrier layerlaterally extends beyond side faces of the power metallization structurein the second region.
 8. The method of claim 4, further comprising:forming an intermediate layer, the intermediate layer being interposedbetween the barrier layer and the passivation layer in the secondregion; and structuring the intermediate layer identically as thebarrier layer in the second region.
 9. The method of claim 8, whereinthe barrier layer comprises TiW, the intermediate layer comprises AlCuand the power metallization structure comprises Cu.
 10. The method ofclaim 4, further comprising: forming an intermediate layer, theintermediate layer being interposed between the passivation layer andthe power metallization structure in the second region.
 11. The methodof claim 4, further comprising: omitting the power metallizationstructure above the barrier layer in the second region.
 12. A method ofmanufacturing a semiconductor device, the method comprising: forming apower metallization structure above the semiconductor substrate; forminga barrier layer between the power metallization structure and thesemiconductor substrate, the barrier layer configured to preventdiffusion of metal atoms from the power metallization structure in adirection toward the semiconductor substrate, the power metallizationstructure being in direct contact with the barrier layer or anelectrically conductive layer formed on the barrier layer in a firstregion; forming a passivation layer interposed between the barrier layerand the power metallization structure in a second section of a secondregion; and structuring the barrier layer as a signal routing structurein a first section of the second region, wherein the first section ofthe second region is spaced apart from the first region by the secondsection of the second region, wherein no metallization structure ispresent above the signal routing structure.
 13. A method ofmanufacturing a semiconductor device, the method comprising: forming abarrier layer above a semiconductor substrate, the barrier layerconfigured to prevent diffusion of metal atoms from above the barrierlayer in a direction toward the semiconductor substrate; forming aprotective layer on the barrier layer and which is configured to preventoxidation of the barrier layer during the structuring; structuring theprotective layer and the barrier layer; after structuring the protectivelayer and the barrier layer, forming a Cu seed layer on the protectivelayer; forming a mask on the Cu seed layer in a second region; forming aCu layer on the Cu seed layer in a first region but not in the secondregion where the mask is present; and after forming the Cu layer,removing the mask and the Cu seed layer from the protective layer in thesecond region.
 14. A method of manufacturing a semiconductor device, themethod comprising: forming a barrier layer above a semiconductorsubstrate, the barrier layer configured to prevent diffusion of metalatoms from above the barrier layer in a direction toward thesemiconductor substrate; forming a protective layer on the barrier layerwhich is configured to prevent oxidation of the barrier layer during thestructuring; structuring the protective layer and the barrier layer;after structuring the protective layer and the barrier layer, forming apassivation layer on the protective layer; removing the passivationlayer in a first region but not in a second region; forming a Cu seedlayer on the protective layer in the first region and on the passivationlayer in the second region; and forming a Cu layer on the Cu seed layerat least in the first region.
 15. The method of claim 14, furthercomprising: before forming the Cu layer, forming a mask on the Cu seedlayer in the second region so that the Cu layer is formed on the Cu seedlayer in the first region but not in the second region where the mask ispresent; and after forming the Cu layer, removing the mask.
 16. Themethod of claim 14, wherein the barrier layer is structured in thesecond region as a signal routing structure, the method furthercomprising: structuring the Cu layer in the second region independentlyof the signal routing structure.
 17. A method of manufacturing asemiconductor device, the method comprising: forming a barrier layerabove a semiconductor substrate, the barrier layer configured to preventdiffusion of metal atoms from above the barrier layer in a directiontoward the semiconductor substrate; forming a protective layer on thebarrier layer which is configured to prevent oxidation of the barrierlayer during the structuring; structuring the protective layer and thebarrier layer; after structuring the protective layer and the barrierlayer, forming a passivation layer on the protective layer; removing thepassivation layer in a first region but not in a second region; andforming a Cu layer on the protective layer in the first region and onthe passivation layer in the second region by physical vapor deposition.18. The method of claim 17, further comprising: removing the Cu layerfrom the passivation layer in the second region.